MarkWhittington writes: "The scenario surrounding the newly released film, "Apollo 18," is fictional and the notion of it being a top-secret Defense Department mission is ludicrous. But NASA actually did, at one time, plan for there to be an Apollo 18 mission to the moon.

Indeed, there Apollo 18, Apollo 19, and Apollo 20 were manifested to fly at one time. But each of these missions was canceled due to congressional budget cuts and a waning public interest in voyages to the moon."